The Kimmel Center for the Performing Arts is laying off 10 percent of its administrative staff.

Seven employees in the arts center's marketing, development, programming, education, and facilities operations departments were told Tuesday that they were being let go; another position will go unfilled.

Ushers, stagehands, security, TicketPhiladelphia, and vice presidents were not among those laid off, Kimmel president Anne Ewers said.

The staff reduction was a response to a combination of a challenging financial picture - lower rent from resident companies such as the Philadelphia Orchestra, reduced state funding, the depressed economy - and an evolving business plan, Ewers said.

"We are really fine-tuning our mission and we . . . need to make sure that our staff is in alignment with that model," she said. "The model, of course, is looking as much as we can toward an earned-revenue approach. All of the many impacts we've had - the loss of funding, the impact of the resident companies, the impact of labor negotiations, the economy - all of those things made it necessary to be nimble to deal with these challenging times."

By an "earned-revenue" model, Ewers means more joint presentations with commercial presenters such as Live Nation, and fewer Kimmel Center Presents concerts that require fund-raising. She said the Kimmel board next week would consider the budget for fiscal 2013, which may have to be tightened in response to the economy; the eight lost positions will save the Kimmel about $500,000 in wages and benefits.

"Layoffs are never easy," she said in a statement. "It's been a sad day for all of us in the Kimmel Center family, and most particularly for the good people we had to let go today. But our sadness is bolstered by certainty - certainty that this is the right thing for us to do."